Section view of the road near the little deer-park at Glenarm, showing how slipping ground was stabilized and protected from the sea.
Copy of a plan which originally appeared in the Second Annual Report of the Commissioners for the Extension and Improvement of Public Works in Ireland (London: 1834).
Inscribed in Image
|Genre||Scientific or Technical illustration|
|Keywords(s)||Bays (Bodies of water), Construction, Rock formations, Seas|
|Published / created||1836|
|Travel Account||A Tour round Ireland [Barrow]|
|Print or manuscript|
|Location of image in copy||p. 53|
|Source copy||National Library of Ireland Ir 9141 b 3|
Related text from travel account
|A few miles farther on [going from Larne towards Glenarm] brought me to the point where the new line of road, carrying on by the Board of Public Works, commences. It is carried in a horizontal line along the sea-coast, at the height of about ten or twelve feet above the highest spring-tides. The advantages of this level road are of the utmost importance to travellers, for the ascents on the old road are not less than one in four, and one in five, rising in no great distance, to six hundred and seventy-five feet above the level of the sea. The engineers had considerable difficulties to contend with, and great labour was necessary to cut down the high cliffs in some places, to fill up valleys and chasms in others, and to prevent the slipping ground from overwhelming them in one or two places; but they have succeeded in overcoming all of them. This magnificent work is now completed as far as Glenarm; and it is intended to carry it on to Ballycastle. The difficulties that have been encountered, and the labour bestowed on it, will best be seen by a section of each, which I shall here copy from the second Annual Report of the Commissioners for the Extension and Improvement of the Public Works of Ireland. In many parts masses of the cliff have been cut away out of [p. 52] beds of solid limestone, to the height of one hundred feet or upwards, leaving a perpendicular precipice on the mountain side, and a solid parapet-wall on the sea-side; the road between these being generally twenty-one feet wide.
The annexed section will best explain what is meant by cutting the cliff. It is at a place called ‘Strait-step Point’. But the most difficult
[image: Strait-step Point]
parts, which they had to contend with, were those where the slipping ground on the sloping sides of the mountain was constantly crumbling away, or rolling down large masses or boulders of limestone [p. 53] or, what was still worse, large quantites of clay in which these boulders were embedded. It was absolutely necessary to contrive some means of preventing these obtruders from blocking up the road. This has been effected by means of an inverted arch, and a retaining wall, or counter-fort, supported by solid pieces of limestone rock deeply embedded in the bank. The boulders that have already fallen serve as a complete barrier against the force of the sea. This slipping-ground occurred mostly at the little deer-park of Glenarm.
[image: Roadway near Glenarm]
In those places where the range of the cliff was interrupted by chasms or glens, down which trickled streams of water, materials were easily obtained from the adjacent rocks to fill up the level of the road; and, at the same time, ample materials to fill up to the height of the parapet, and afford a barrier against the waves of the sea. The following sketch will convey an idea in what manner these fillings up were accomplished.
[p. 54] The whole of this coast presents to the sea a bold limestone front, which assumes a more romantic form from the summit of the cliff being sometimes pinnacled in such a manner as to resemble chimney-tops, a name which, in fact, in such places they have acquired. In other parts the cliff is crowned with a stratum of basalt or trap, not unfrequently taking the form of prisms, or regular polygonal pillars. At White Bay the cliffs are beautifully white; so much so that, if in England, the observer would at once pronounce them to be chalk.
[image: Cliffs, White Bay]
[p. 55] We have heard a great deal of the fine road which Buonaparte is supposed to have made, but which he, in fact, only improved, along the left bank of the Rhine; the latter is certainly very well executed, but I do not think it at all superior to the one in question; the mere labour being, however, more severe in the one than the other, inasmuch as basalt is more difficult to manage than limestone. In the Irish road the same level has been preserved; and a strong parapet throughout, together with its glacis, prevent the encroachment of the sea, which is of great importance to the traveller, by affording a protection against accident. [pp. 51-55]